This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Diffuse Optical Imaging and Spectroscopy (DOI, DOS) are emerging diagnostic techniques that quantitatively measure the concentration of deoxy-hemoglobin, oxy-hemoglobin, water, and lipid in cm-thick tissues. In early-stage clinical studies, DOI and DOS have been used to characterize breast tumor biochemical composition and monitor therapeutic response in neoadjuvant chemotherapy patients. In this work, we investigate whether DOS measurements obtained early in a neoadjuvant chemotherapy regimen can predict final, post-surgical pathological response in breast cancer patients.